All ‘ UNESCO ‘ s UN agency for education, science and culture , are convinced: 2015 will go down in history as the ‘ year of beginning of a new era, the Photonics , and will close the old era of electronics and enable a new phase of technological development. The selfie, portraits swarming on social networks, made from the CCD sensors of compact digital cameras, which are not the pop version and still pretty rough this new era in which lasers, in optical fibers or photovoltaic panels the first demonstrations of its enormous potential.
In the era of photonics , as its name implies, photons replace electrons as the fundamental particles of the latest technologies. And because the photons are “atoms of light” here that UNESCO has chosen the 2015 “International Year of the light”.
The future, therefore, will be a sort of new Renaissance, dominated by light and application (also in the arts?) of the scientific laws of optics. Except that the geometric, applied by “scientists artists” as Piero della Francesc a, give more space quantum optics, which has among its “scientists artists” Richard Feynman, Nobel Prize for Physics in 1965. But the light is still (more than ever) the focus of the science of the tip, as demonstrated by the fact that the last of the Nobel Prizes in Physics, that of 2014 , it was won by the discoverers of the “blue light” that enables the development of LEDs used in our smartphones and our tablet (which is obsolete electronic technologies) and they sent retire the old incandescent bulbs.
But it is far from the first noises that science is “visual science”: science of light. And, in fact, one of the first and of the greatest scientists of all time, Euclid , active in Alexandria between the fourth and third centuries BC, with the ” science of light “inaugurates science tout court. And not only when writing the optics, the pri mo book dedicated to rules governing the transmission of light. But when King dige Elements, considered the founding act of the modern geometry.
And what is the geometry but “visual mathematics,” study of the forms and their relationships in space? Indeed, even Aristotle , the largest of Euclid fifteen years or so, he was interested in the physics and physiology of vision.
Claiming to see a object must be that between the eye and the object is present a transparent medium, such as air, “full of light” , because the eye does not see in the dark. There is in this proposal of the philosopher of Stagira a first consideration of the “nature of light”: not the substance itself, but damn transparent substances such as air or water. Yeah, but What is light? is the answers given to this question in the course of its history that physics has given much of his own progress. And the answers which will continue to depend on its future and the future of photonic technologies.
The first to respond to Aristotle’s own Euclid. The light is not in the objects we see, but in the eye that sees.
It’s him, the eye, which emanates light rays that reach the illuminated object. The vision is nothing more than the re back to our eye the rays reflected from objects that are affected. Because the rays and those reflected propagate in a straight line, that we can develop more mathematically rigorous optics. Euclid is not alone in the Hellenistic world to deal with light. The optics Ptolemy , lived almost half a millennium after Euclid, has long influenced the Islamic culture and the West. But if the study of practical light transmission involved mon do the whole, it is only in the ninth century that someone is able to make news on his na ture. It alKindi the “first Islamic philosopher” that occurs experimentally which of the proposed theories of the two Greeks is best to explain the known facts. AlKindi , is that Aristotle’s theory is unable to explain the influence in perception between object and viewing angle, while the geometric theory of Euclid explains all the known facts and, therefore, must be considered the best.
The light, then, is not an accident . Al Kindi, along with another Islamic scientist, Alhazen, can be rightly CONSIDE rato one of the fathers noble optics scientific ca. Certainly both influence the thinking and work of the first natural philosophers appeared in Europe in the thirteenth century. In particular the group of Franciscans, called for appun to “philosophers of light”, which in Oxford give life to a long and successful series of studies on optics. The first is Robert Grosseteste: light, he says, is a pure form of matter: “first form of the raw material cre ate” that spreads instantaneously and spherical. The diffusion of light can be in dagata with the methods, exact, geometry. Indeed, it is possible to establish the full description of the physical world geometrical optics. His disciple, Roger Bacon, corrects it in a detail: the light moves at a fast ty certainly very large, but finite.
After the “great crisis of the fourteenth century,” the Renaissance marked by the “return of light”. And not just in a metaphorical sense. Scientific research starts in Europe in the fifteenth century with studies on geometrical laws of perspective made by Leon Battista Alberti, Luca Pacioli, Piero della Francesca and their practical application in the work of Brunelleschi, Donatello and Masaccio. They are the ones to initiate the European phase of the research that has been defined, not by chance, “visual science”. At least two centuries in the name of light which preceded the scientific revolution of the seventeenth percent, which owes much to the improvement in 1609, the telescope by Galileo. A new feature that allows you to see in heaven, read ally, “things never seen before.” And it is accompanied by the invention of the microscope which, in turn, allows you to see “things never seen before” in the microscopic world. These are innovations for lighting technology that, in the words of Ernst Cassirer, “divide the ages.” It is also a result of these technologies, which incorporates scientific reflection on the ambiguous nature of light. The light is made of waves, offers Christiaan Huygens in 1678.
Not at all, responds Isaac Newton, with his Optics of 1704 : light consists of tiny particles propagate in a straight line. Not at all, argue in the early nineteenth century Thomas Young and Fresnel AugustinJean, offering a new theory, wave, light. The idea that light is a form of radiant energy emanating from the matter is codifi ed in the second half of the nineteenth century by Ja mes Maxwell, in that his famous theory that unifies optics, electricity and magnetism. It seems the word tomb ancient question: light is a wave.
But after a few years and so, in the 1905 , Albert Einstein shows that everyone and no one reason: light has a double and ambiguous nature . Composed as it is of “ light quanta” , discrete objects but no mass, which behave as particles and as waves. Later the “light quanta” are called photons. Einstein founded his theory of relativity on a narrow optical postulate: nothing can travel faster than the speed of light.
Ten years later, in 1915 with theory of general relativity , Einstein shows that the photons and material objects with mass do not move in space and time, but with their presence and their dynamics determine the same geometry of spacetime. The reflection on the ambiguous nature of light and its behavior has spawned a new and unexpected view of the universe.
It is not over. With the development of quantum physics, from years 20, I discover no features of entanglement: two photons can be linked even at a distance and one can “know” what the other is instantly breaking the law against actions and transmit information at speeds faster than light.
The light that makes a mockery of itself. is the prelude to the “teleportation” instantaneous transmission distance considered absurd but first demonstrated experimentally by Alain Aspect (for rooms of a few centimeters) and then by Anton Zeilinger, for distances of hundreds of meters on either side of the Danube. Recently, in 2012, the news of a new success: the “teleportation” of photons were worked over a distance of 143 km, between the islands of La Palma and Tenerife in the Canary Islands. By controlling the ambiguous nature of light, physicists have made new objects and already widely used, such as lasers and optical fibers. But, perhaps, in the new era photonics new technological frontier will be the control of a seemingly absurd: the “teleportation”, the instantaneous action at a distance between “light quanta”.
@ pietrogreco1
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